Change the smoke target to create a test-results directory. This was
done implicitly by the test-lib before my "test-lib: Don't write
test-results when HARNESS_ACTIVE" patch, but after that smoking from
the pu branch hasn't worked.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>